I noticed that my symbols changed slightly when I imported from ArcMap to ArcGIS Pro. I didn't find this documented anywhere. The layer is a polyline with a referenced style symbol. ArcGIS Pro imported layer but the line weights are all different.
ArcGIS Pro Migration – Resolving Layer Symbology Changes from ArcMap
arcgis-proarcmapsymbology
Related Solutions
Symbol rotation for point markers is defined when you click on the symbol and view its properties. Under Angle alignment is a drop box showing Display and Map. You can augment the rotation by defining which one you want.
This is set per individual symbol, so the process goes like this: Click the symbol in the Contents Pane (Or open the Symbology pane and click the symbol) You'll see the Gallery and Properties tabs. Click Properties There are three tabs under Properties: Symbol / Layers / Structure. Click Symbol. Next are two drop-downs: Appearance and Halo. Click Appearance. There you will see Angle Alignment.
Display - Point symbol is rotated according to your screen. Map - Point symbol is rotated according to the data frame (map properties)
You can do it from Symbology tab, just click in More to access to Format all symbols:
If you want to format just some symbols, select them (you can use SHIFT or CONTROL to select several items), right click and select Format symbol(s)
Best Answer
Seems like a BUG, but you can try to save the symbology as a layer file in ArcMap and import it in Pro, also check this https://community.esri.com/t5/arcgis-pro-ideas/arcgis-pro-quot-export-map-styles-quot-for-bulk/idi-p/937605.